* {
  margin: 0;
  padding: 0;
}

nav {
  width: 100%;
  height: 50px;
  line-height: 45px;
  text-align: center;
  background-color: #1E9FFF;
}

a {
  text-decoration: none;
  color: #BCE2FF;
}

.active {
  border-bottom: 5px solid #BCE2FF;
  color: #ffffff;
}
.login a:hover{
  color: #ffffff;
}


/* 
***超小屏幕（手机<768px)
***小屏幕(平板≥768px)
***中等屏幕(桌面≥992px)
***大型屏幕(桌面≥1200px)
*/

/* 超小屏幕768 */
@media screen and (max-width: 768px) {
  nav{
    text-align: left;
  }
  .nav-logo{
    height: 50px;
  }
  .logo{
    display: none;
  }
  .nav-logo>a:last-child{
    display: inline-block;
    float: right;
  }
  .nav-logo>a:last-child img{
    width: 40px;
  }
  .menu>li ,.login>li{
    list-style: none;
    background-color: #1E9FFF;
  }
}
.logo>li{
  list-style: none;
  float: left;
}
.logo img{
  height: 50px;
}
.nav-logo img{
  height: 50px;
}
/* 小屏幕 */
@media screen and (min-width: 768px) {
  nav{
    text-align: left;
  }
  .nav-logo{
    height: 50px;
  }
  .logo{
    display: none;
  }

  .nav-logo>a:last-child{
    display: inline-block;
    float: right;
  }
  .nav-logo>a:last-child img{
    width: 40px;
  }
  .menu>li ,.login>li{
    list-style: none;
    background-color: #1E9FFF;
  }
}

/* 中等屏幕 */
@media screen and (min-width: 992px) {
  .nav-logo{
    display: none;
  }
  .menu{
    display: block;
  }
  .login{
    display: block;
  }
  .logo{
    display: block;
  }
  .nav-bar{
    width: 80%;
    margin: 0 auto;
  }
  .menu>li ,.login>li{
    margin-left: 25px;
    list-style: none;
    float: left;
  }
  .menu{
    float: left;
    text-align: center;
  }
  .login{
    float: right;
  }
  .menu>li a{
    display: inline-block;
    height: 100%;
    width: 150%;
  }
}

/* 大型屏幕 */
@media screen and (min-width: 1200px) {
  .nav-logo{
    display: none;
  }
  .nav-bar{
    width: 80%;
    margin: 0 auto;
  }
  .menu>li ,.login>li{
    margin-left: 25px;
    list-style: none;
    float: left;
  }
  .menu{
    float: left;
  }
  .login{
    float: right;
  }
  .menu>li a{
    display: inline-block;
    height: 100%;
    width: 150%;
  }

}